Implement, as best as you can, the identity function in your favorite language
(or the second favorite, if your favorite language happens to be Haskell).

```
const identity = x => x;
```

Implement the composition function in your favorite language.
It takes two functions as arguments and returns a function that is their composition.

```
const composition = (f, g) => (x => g(f(x)))
```

Write a program that tries to test that your composition function respects identity.

```
const f = x => `f(${x})`;
composition(f, identity)('x'); //"f(x)"
composition(identity, f)('x');
```
Is the world-wide web a category in any sense? Are links morphisms?
Yes.

Is Facebook a category, with people as objects and friendships as morphisms?
Yes, kind of.

When is a directed graph a category?